Arrangement structure of inclination angle sensor

ABSTRACT

In a vehicle of a type which does not bank a vehicle body at the time of turning, an inclination angle sensor is provided which receives the least influence of a centrifugal force at the time of turning. In a four-wheeled buggy that includes a vehicle body frame, four longitudinal wheels including front wheels and rear wheels are provided together with an engine, a fuel tank and a fuel pump. A steering shaft is connected to a steering handle with an inclination angle sensor arranged above a seat and being positioned in front of the steering shaft. Accordingly, the inclination angle sensor is hardly influenced by a centrifugal force at the time of turning.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 USC 119 to JapanesePatent Application No. 2005-252863 filed on Aug. 31, 2005 the entirecontents of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an arrangement structure of aninclination angle sensor which is suitably applicable to a vehicle of atype which turns a vehicle body of a four-wheeled buggy while preventingthe vehicle body from banking.

2. Description of Background Art

A vehicle is known that includes an inclination angle sensor fordetecting an inclination of a vehicle body in the lateral direction forstopping an engine. In a vehicle of a type which turns the vehicle bodywithout banking the vehicle body, the inclination angle sensor is liableto be easily influenced by a centrifugal force during turning. Thus, aninclination angle sensor is known which is arranged in the vicinity ofthe center of the turning to avoid the influence of the centrifugalforce. See, JP-A-2005-178420.

In the above-mentioned conventional example, the center of turning inthe vehicle is considered to be positioned above an axis of the left andright front wheels and the inclination angle sensor is positioned in thevicinity of the center of turning of the vehicle body. Thus, a recessedportion is formed in a front end of a fuel tank and the inclinationangle sensor is arranged in the recessed portion.

However, in this case, to mount the inclination angle sensor, it isnecessary to change a shape of the fuel tank. Further, it is necessaryto change the fuel tank for each type of vehicle.

Further, it is desirable that the inclination angle sensor is arrangedin the vicinity of or close to the center of turning thus reducing theinfluence of a centrifugal force.

SUMMARY AND OBJECTS OF THE INVENTION

Accordingly, it is an object of the present invention to arrange theinclination angle sensor closer to the vicinity of the center of turningwithout requiring a large change with respect to vehicle bodyconstitutional parts.

To overcome the above-mentioned drawback, according to an embodiment ofthe present invention an arrangement structure of an inclination anglesensor is directed to a vehicle which includes a frame with at leastthree wheels which are supported on the frame. A steering shaft isconnected to a steering handle. The vehicle includes an inclinationangle sensor wherein the inclination angle sensor is arranged above aseat and, at the same time, in front of the steering shaft and above anaxis of a front wheel.

According to an embodiment of the present invention, a radiator isprovided with a reservoir tank being arranged behind the radiator. Theinclination angle sensor is arranged behind the reservoir tank.

According to an embodiment of the present invention, the inclinationangle sensor is mounted on a cross member which is arranged to extendbetween left and right sides of a vehicle body frame and supports anupper end of a front shock absorber of a front-wheel suspension.

In a vehicle that includes at least three wheels, the wheels are allowedto slide and turn while preventing the vehicle body from banking at thetime of turning. Thus, a centrifugal force which is generated duringsuch turning affects the inclination angle sensor. However, theinclination angle sensor of the present invention is arranged in frontof the steering shaft and above the axis of the front wheel. “Thus, theinclination angle sensor is arranged closer to the vicinity of thecenter of turning of the vehicle body. Accordingly, the inclinationangle sensor is arranged at a position where at least a centrifugalforce is applied to the inclination angle sensor at the time of turningthe vehicle. Thus, the influence of the centrifugal force can bereduced. Further, it is possible to arrange the inclination angle sensorwithout requiring a change of other vehicle body constitutional partwhich requires a particular mounting part.

According to an embodiment of the present invention, the reservoir tankof the radiator is provided behind the radiator and the inclinationangle sensor is arranged behind the reservoir tank. Thus, it is possibleto arrange the inclination angle sensor at a position where theinclination angle sensor hardly receives any thermal damage from theradiator.

According to an embodiment of the present invention, the inclinationangle sensor is mounted on the cross member which supports the upper endof the front shock absorber. Thus, it is unnecessary to prepareparticular mounting parts whereby the number of parts can be reducedand, at the same time, the change of other vehicle-body constitutionalparts becomes unnecessary.

Further, by mounting the inclination angle sensor on the cross memberwhich supports the upper end of the front shock absorber, it is possibleto arrange the inclination angle sensor above an axis of the front wheelas viewed in a side view. Thus, it is possible to arrange theinclination angle sensor closer to the vicinity of the center of turningof the vehicle body.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a side view of a four-wheeled buggy according to anembodiment;

FIG. 2 is a plan view of the four-wheeled buggy according to theembodiment;

FIG. 3 is a front view of the four-wheeled buggy according to theembodiment;

FIG. 4 is a view showing a mounting portion of an inclination anglesensor;

FIG. 5 is a front view of the inclination angle sensor; and

FIG. 6 is a side view of the inclination angle sensor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an embodiment of the present invention is explained inconjunction with drawings. Here, directions such as front, rear, leftand right in the following explanation are based on the directions of avehicle in use unless otherwise specified.

FIG. 1 is a left side view of a four-wheeled buggy according to theembodiment. The four-wheeled buggy is a saddle-riding-type vehicle fortraveling on irregular ground. The vehicle includes a pair of left andright front wheels 2 and a pair of left and right rear wheels 3 whichare low pressure balloon tires having relatively large diametersarranged on front and rear portions of the vehicle body frame 1 thusensuring a large minimum ground height for enhancing the operationalability mainly on irregular ground.

At an approximately center position of the vehicle body frame 1, anengine 5 is mounted which includes a forwardly inclined cylinder 4. Theengine 5 is a water-cooling type single-cylinder engine. A crankcase 6which forms a lower portion of the engine 5 also functions as atransmission case, and a chain 9 extends between and is wound around anoutput sprocket wheel 7 which is formed on a rear portion of thecrankcase 6 with a driven sprocket wheel 8 being provided on therear-wheel side whereby the rear wheels 3 are driven by the chain.

The rear wheels 3 are suspended to a rear portion of the vehicle bodyusing a double wishbone method.

Supplying of a mixed gas to a cylinder head 13 of the engine 5 isperformed from a throttle body 14 which is arranged behind the cylinderhead 13. The throttle body 14 includes an injector (omitted from thedrawing, see FIG. 2) which injects fuel to the inside of an intakepassage by an electric control and, at the same time, introduces outsideair therein from an air cleaner 15 which is arranged behind the throttlebody 14. Fuel is supplied from a fuel tank 16 which is arranged abovethe cylinder head 13 by way of a fuel pump (described later).

Further, a proximal end portion of an exhaust pipe 17 is connected to afront portion of the cylinder head 13, and the exhaust pipe 17 extendsalong one side of the cylinder head 13 and is connected to a muffler 18which is arranged on a rear portion of the vehicle body.

A steering shaft 20 is mounted on a front portion of the vehicle bodyand is rotated by a handle 21 arranged on an upper end portion thereof.The steering shaft 20 is arranged obliquely in the upward and rearwarddirection with a lower end portion thereof forming a center of turning.The steering shaft 20 is positioned in the vicinity of the center of thefront wheel 2 as viewed in a side view. At the time of turning, the leftand right front wheels 2 are steered by a rotation of the steering shaft20 using a conventional steering mechanism.

A front portion of the steering shaft 20 is covered with a front cover22 made of resin. On the inside of the front cover 22, from the frontside, a radiator 23 is provided for cooling the engine. A reservoir tank24 of the radiator 23 are arranged in this order. Further, aninclination angle sensor 25 is arranged behind the reservoir tank 24.The inclination angle sensor 25 is arranged in a state wherein theinclination angle sensor 25 is concealed by the back surface of thereservoir tank 24 as viewed in a front view.

An air cleaner 15 is arranged below a rear-side portion of a seat 26behind the lowest portion of the seat 26 with a snorkel 15 a extendingupwardly from a rear portion of the air cleaner 15 and an opening formedon an upper end portion of the snorkel 15 a projects up to a relativelyhigh position below the seat 26. A battery case 27 is arranged betweenthe air cleaner 15 and the throttle body 14. A fuel pump 28 is arrangedbelow the fuel tank 16 and in front of the engine 5.

A fuel intake port formed in an upper portion of the fuel pump 28 and afuel takeout port formed in a bottom portion of the fuel tank 16 areconnected by way of a communication pipe 28 a in a straight manner witha short distance therebetween. On the other hand, a fuel discharge portof the fuel pump 28 and an injector of the throttle body 14 areconnected by way of a fuel supply pipe 28 b. The fuel supply pipe 28 bextends upwardly from the fuel discharge port which is arranged in anupper portion of the fuel pump 28 and is thereafter bent toward a rearportion and extends rearwardly to arrive at the injector.

When the fuel pump 28 is operated, the fuel sucked from the fuel tank 16is pressurized to a predetermined fuel pressure and is thereaftersupplied to the injector by way of the fuel supply pipe 28 b. The fuelis injected by the operation of the injector thus being supplied to thecylinder head 13 together with the outside air which is introduced fromthe air cleaner 15.

The vehicle body frame 1 includes an upper frame 30 and a lower frame 31which are arranged longitudinally to be approximately parallel to eachother. The front down frames 32 are arranged obliquely in the frontwardand downward direction by bending a front portion of the upper frame 30with a rear down frame 33 which is arranged obliquely in the rearwardand downward direction by bending a rear portion of the upper frame 30and extends through the engine 5. The frames are contiguously formed ina closed-loop as viewed in a side view.

In the vicinity of a connection portion between a front end portion ofthe upper frame 30 and an upper portion of the front down frames 32, anupper bracket 34, which supports an upper portion of the steering shaft20, is formed. A lower bracket 35 supports a lower end portion of thesteering shaft 20 and is supported on the lower frame 31 at the vehiclebody center.

A reinforcing pipe 36 is formed obliquely in the frontward and upwarddirection between a lower portion of the front down frames 32 and afront portion of the lower frame 31 thus forming a triangularreinforcing portion on a front lower portion of the vehicle body frame1. A stay 37, which supports an arm member for a double wishbone typefront wheel suspension device, is formed on the reinforcing portion. Afront protector 38 is provided that is mainly made of a steel pipe.

A reinforcing pipe 39 is provided for connecting an intermediate portionof the front down frames 32 and a front portion of the lower frame 31.An upper end portion of the front shock absorber 19 of the front wheelsuspension device is supported on a cross member 51 (described later)which is formed on an intermediate portion of the front down frames 32which is arranged in the vicinity of an upper end portion of thereinforcing pipe 39. The upper end portion of the front shock absorber19 is positioned above an axis O of the front wheels 2 as viewed in aside view. The axis O corresponds to the center of an axle of the frontwheels.

A rear portion of the lower frame 31 is bent in the vicinity of a lowerend portion of the rear down frame 33 to form a rear frame 40 whichextends obliquely in the upward and rearward direction. A rear portionof the rear frame 40 is connected to a longitudinally intermediateportion of a seat rail 41 which extends rearwardly and approximatelyhorizontally from the vicinity of a connection portion of a rear endportion of the upper frame 30 and the rear down frame 33.

The seat rail 41 includes an overhang portion 42 which extends furtherrearwardly from a portion to which an upper end portion of the rearframe 40 is connected. Thereafter, the seat rail 41 is bent obliquely inthe downward direction. The overhang portion 42 is formed and isconnected to a rear end of a rearward extending portion 43 of the lowerframe 31.

The rearward extending portion 43 extends rearwardly from the vicinityof the connection portion of a rear portion of the lower frame 31 andthe rear frame 40, while a rear end portion of the rearward extendingportion 43 is bent upwardly and is connected with a lower end of theoverhang portion 42 by way of a connection portion 44. A reinforcingportion pipe 45 is connected between a vertically intermediate portionof the rear frame 40 and the connection portion 44 and is arranged abovethe rearward extending portion 43 approximately parallel to the rearwardextending portion 43. The reinforcing pipe 45 and the rearward extendingportion 43 support the arm member for double wishbone type rear wheelsuspension device and include a stay 46 provided for this purpose.

FIG. 2 is a plan view of the vehicle body frames 1. The above-mentionedvehicle body frames 1, as viewed in a plan view, are configured suchthat a pair of left and right vehicle body frames 1 are arranged whilesandwiching a vehicle body center C therebetween and left and rightportions of the vehicle body frame 1 are connected by cross members 50to 56 thus forming an integral body as a whole. The members whichconstitute the vehicle body frame 1 are made of a steel pipe or thelike.

Here, although omitted from this drawing, the steering shaft 20 isoverlapped to the vehicle body center C.

Further, the inclination angle sensor 25 is also positioned on thevehicle body center. The inclination angle sensor 25 is used fordetecting that the inclination of the vehicle body reaches apredetermined angle.

A heat blocking cover 29 is arranged between the fuel tank 16 and theengine 5. Above the heat blocking cover 29, the fuel supply pipe 28 b islongitudinally arranged and a rear end portion of the fuel supply pipe28 b is connected to an injector 14 a of the throttle body 14. The fuelsupply pipe 29 b is fixed to the heat shielding cover 29 at suitablepositions using clamps.

FIG. 3 is a front view of the vehicle body frame 1, wherein on a frontportion of the vehicle body, the upper bracket 34, which projectsupwardly from the cross member 51 which extends between the left andright upper frames 30, is mounted such that the upper bracket 34 isarranged above the vehicle body center C. The inclination angle sensor25 is provided for mounting the front shock absorber 19 (FIG. 1) of thefront wheel suspension device and is supported on a center portion ofthe cross member 51 in the lateral direction which traverses the leftand right front down frames 32 and is positioned on the vehicle bodycenter C. This position of the inclination angle sensor 25 is arrangedon the vehicle body center, in front of the steering shaft 20 and abovethe axis O of the front wheels 2 as viewed in a side view. Accordingly,the inclination angle sensor 25 is positioned close to the vicinity ofthe center of turning of the vehicle body.

FIG. 4 is an enlarged side view of the cross member 51, wherein thecross member 51 has an approximately inverse U-shape as viewed in a sideview and is raised upwardly from the front down frames 32. Further, thecross member 51 has a lower portion thereof welded to an outerperipheral portion of the front down frames 32. A lower end portion of aback portion 51 a of the cross member 51 forms a downward projectionportion 51 b at a lateral center portion thereof and a nut 51 c iswelded to the downward projecting portion 51 b. By mounting theinclination angle sensor 25 on the nut 51 c, the inclination anglesensor 25 can be supported at the vehicle body center.

As shown in FIGS. 5 and 6, the inclination angle sensor 25 includes anacceleration sensor which includes a float 61 as a pendulum in theinside of a casing 60. The casing 60 accommodates a detection circuit 63in the inside of a box portion 62 which forms an upper portion of thecasing 60, while the float 61 is accommodated in the inside of a spaceforming portion 65 which forms the lower portion of the casing 60.

The space forming portion 65 has a vessel-like shape with an upperportion thereof open-ended and includes front and rear wall portions 66,66 which form a U-shaped profile as viewed in a front view (frontsurface view) and an outer peripheral wall portion 67 which connectsouter peripheries of the front and rear wall portions 66, 66 thusforming an accommodating space 69 therein. Rubber mounts 70 are mountedon mounting projection portions 67 a which are formed on both sideportions of the casing 60, while the mounting projection portions 67 aare mounted on nuts 51 c of the cross member 51 by using bolts 71 (FIG.6) here with a vibration damping effect.

The float 60 is a member having a semicircular shape which is pivotallymounted on a swinging shaft 72 at the approximate center in the insideof the accommodating space 69 and is swingably supported on the casing60, wherein the pivotally mounting portion functions as a swingingfulcrum. A lower portion of the outer peripheral wall portion 67 has anarcuate shape which corresponds to an arcuate portion of the float 60.Damper oil for reducing the swinging movement of the float 61 is filledin the inside of the accommodating space 69.

A magnet 73 is embedded in left and right end portions of the float 61and magnetic sensors 74 are formed on the left and right sides of anupper end portion of the float 61 in the inside of the accommodatingspace 69. When the float 61 reaches a predetermined swinging angle, themagnetic sensor 74 detects a magnetism of the approaching magnet 73.Thus, it is possible to detect that the vehicle body is inclined up to apredetermined angle.

The swinging shaft 72 of the float 61 is arranged parallel to thelongitudinal direction of the vehicle body. However, by adjusting theposition of the center of gravity of the float 61 or the like, inaddition to a case wherein the vehicle body is inclined in the lateraldirection and even in a case wherein the vehicle body is inclined in thelongitudinal direction, the float 61 is allowed to swing. Hereinafter,it is assumed that when the vehicle body is in a state wherein thelongitudinal and lateral inclinations are set to 0° (upright state) andonly gravity acts as a force on the float 61, the float 61 is positionedat a neutral position of a swinging range in the accommodating space 69.

When the vehicle body is inclined in the longitudinal or lateraldirection, the float 61 swings with respect to the casing 60. When theswinging of the float 61 reaches a predetermined angle, based on adetection signal of the magnetic sensor 74, the detection circuit 63judges whether the swinging of the vehicle body reaches a predeterminedangle or not. When it is judged that the vehicle body is inclined by thepredetermined angle, by way of ECU (omitted to be shown in the drawing),a predetermined engine control such as an ignition cut or a fuelinjection cut is performed.

The four-wheeled buggy according to this embodiment does not turn thevehicle body by banking as in a motorcycle. Thus, even when the vehiclebody is in a substantially upright state by the action such as acentrifugal force or the like during a turning operation, there arises acase wherein the float 61 of the inclination angle sensor 25 swings. Tocope with such a situation, a detection angle of the inclination anglesensor 25 of the present invention is set larger than the detectionangle of the inclination angle sensor 25 used in a motorcycle. Here, thedetection angle means a swinging angle from a neutral position of thefloat in detecting the predetermined inclination angle of the vehiclebody.

Further, in the inclination angle sensor 25, a delay time is provideduntil the detection circuit 63 detects the inclination angle of thevehicle body thus preventing the inclination angle sensor 25 frommisjudging that the inclination of the vehicle body reaches thepredetermined angle when the float 61 largely swings and temporarilyreaches the detecting angle at the time of a turning operation. Thedelay time is set to a period longer than the period wherein the float61 is held at the maximum swinging position by the centrifugal force atthe time of turning. Accordingly, when a state in which the float 61 isinclined to the predetermined angle is continued for the predeterminedtime, it is judged that the vehicle body is inclined to thepredetermined angle.

Next, the function of this embodiment is explained. As shown in FIGS. 1and 3, the inclination angle sensor 25 is arranged on the cross member51 arranged in front of the steering shaft 20 on the vehicle body centerC. Further, the inclination angle sensor 25 is arranged in front of thesteering shaft 20 and above the axis O of the front wheels 2 as viewedin a side view on the vehicle body center C. Thus, in the four-wheeledbuggy in which a vehicle body does not bank at the time of turning, itis possible to arrange the inclination angle sensor 25 closer to thevicinity of the center of turning thus restricting an influence by thecentrifugal force or the like at the time of operation as small aspossible. Accordingly, it is possible to arrange the inclination anglesensor 25 at the most suitable position in the vehicle which adopts sucha type. Thus, it is possible to prevent the inclination angle sensor 25from misjudging the inclination of the vehicle body by the centrifugalforce or the like thus enabling the favorable engine control.

Further, since the inclination angle sensor 25 is mounted on aconventionally existing cross member 51, the inclination angle sensor 25can be arranged without requiring a change of other vehicle-bodyconstitutional parts such as preparation of particular mounting parts orthe like whereby the number of parts can be reduced. In addition, at thesame time, the change of other vehicle-body parts becomes unnecessary.Further, since the cross member 51 supports an upper end of the frontshock absorber 19, by mounting the inclination angle sensor 25 on thecross member 51, it is possible to arrange the inclination angle sensor25 above the axis O of the front wheels 2 as viewed in a side view.

Further, even in the inclination angle sensor 25 which detects theinclination of the vehicle body in the lateral direction, when thevehicle is inclined in the longitudinal direction, the float 61 isallowed to swing in either of the left and the right directions.Accordingly, it is possible to detect the inclination of the vehiclebody in the longitudinal direction. Thus, the engine control which canwidely cope with the inclination of the vehicle body can be realized.Further, since the delay time is prepared for detection by the detectioncircuit 63, only when the state in which the swinging of the float 61reaches the detection angle is continued for the predetermined time, itis detected that the inclination of the vehicle body is thepredetermined angle. Accordingly, momentary swinging of the float 61 canbe excluded as a noise thus further increasing the detection accuracy.Further, since the detection angle of this embodiment is set larger thanthe detection angle of a motorcycle, it is possible to further enhancethe detection accuracy.

Further, the radiator 23, the reservoir tank 24 and the inclinationangle sensor 25 are arranged in order from the front side of the vehiclebody and, at the same time, the inclination angle sensor 25 is arrangedsuch that the inclination angle sensor 25 is concealed by the backsurface of the reservoir tank 24 as viewed in a front view. Thus, it ispossible to prevent the exhaust heat of the radiator 23 from directlyreaching the inclination angle sensor 25 thus preventing the inclinationangle sensor 25 from receiving thermal damage by the radiator 23.Accordingly, this construction can also contribute to enhancing thedetection accuracy by the inclination angle sensor 25.

The present invention is not limited to the above-mentioned embodimentand various modifications can be made. For example, it is not alwaysnecessary to prepare the mounting position of the inclination anglesensor 25 on the cross member 51, so long as the mounting position ofthe inclination angle sensor 25 is arranged in front of and in thevicinity of the steering shaft 20. Further, the inclination angle sensor25 may be offset to one side of the vehicle body instead of beingarranged on the vehicle body center.

Further, the structure of the inclination angle sensor 25 is also notlimited to the structure of this embodiment. A conventional structuremay be utilized. Further, a vehicle to which the present invention isapplicable can be various types of vehicles as long as the vehicle isprovided with at least three wheels and does not bank at the time ofturning.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. An arrangement structure of an inclination angle sensor mounted on avehicle which includes a frame, at least three wheels which aresupported on the frame, and a steering shaft which is connected to asteering handle comprising: an inclination angle sensor, saidinclination angle sensor being arranged in front of the steering shaftand above an axis of a front wheel.
 2. The arrangement structure of aninclination angle sensor according to claim 1, and further including aradiator and a reservoir tank, arranged behind the radiator, saidinclination angle sensor being arranged behind the reservoir tank. 3.The arrangement structure of an inclination angle sensor according toclaim 1, wherein the inclination angle sensor is mounted on a crossmember which is arranged to extend between left and right sides of avehicle body frame and supports an upper end of a front shock absorberof a front-wheel suspension.
 4. The arrangement structure of aninclination angle sensor according to claim 1, wherein the inclinationangle sensor is arranged in the vicinity of the center of turning forreducing the influence of centrifugal force on the inclination anglesensor.
 5. The arrangement structure of an inclination angle sensoraccording to claim 1, wherein said frame includes front down framemembers and a front portion of the lower frame with a cross member beingdisposed between the front down frame members at a position displacedupwardly relative to the lower frame and the inclination angle sensor ismounted adjacent to the cross member.
 6. The arrangement structure of aninclination angle sensor according to claim 5, wherein the cross memberis disposed at an intermediate portion of the front down frame members.7. The arrangement structure of an inclination angle sensor according toclaim 1, wherein the inclination angle sensor is concealed by a surfaceof the reservoir to prevent exhaust heat from the radiator fromthermally damaging the inclination angle sensor.
 8. The arrangementstructure of an inclination angle sensor according to claim 6, whereinthe cross member is approximately an inverse U-shape as viewed from theside with a lower portion of the cross member being welded to the frontdown frame members.
 9. The arrangement structure of an inclination anglesensor according to claim 8, wherein the inclination angle sensorincludes a float having a semicircular shape that is pivotally mountedon a swinging shaft mounting nut with a damper being provided forlimiting the swinging movement of the float.
 10. The arrangementstructure according to claim 9, wherein the swinging shaft of the floatis arranged substantially parallel to a longitudinal direction of thevehicle body.
 11. An arrangement structure comprising: a frame of avehicle; an inclination angle sensor mounted on the frame; and asteering shaft operatively connected to a steering handle; saidinclination angle sensor being positioned in front of the steering shaftand above an axis of a front wheel.
 12. The arrangement structureaccording to claim 11, and further including a radiator and a reservoirtank, arranged behind the radiator, said inclination angle sensor beingarranged behind the reservoir tank.
 13. The arrangement structureaccording to claim 11, wherein the inclination angle sensor is mountedon a cross member which is arranged to extend between left and rightsides of a vehicle body frame and supports an upper end of a front shockabsorber of a front-wheel suspension.
 14. The arrangement structureaccording to claim 11, wherein the inclination angle sensor is arrangedin the vicinity of the center of turning for reducing the influence ofcentrifugal force on the inclination angle sensor.
 15. The arrangementstructure according to claim 1, wherein said frame includes front downframe members and a front portion of the lower frame with a cross memberbeing disposed between the front down frame members at a positiondisplaced upwardly relative to the lower frame and the inclination anglesensor is mounted adjacent to the cross member.
 16. The arrangementstructure according to claim 15, wherein the cross member is disposed atan intermediate portion of the front down frame members.
 17. Thearrangement structure according to claim 11, wherein the inclinationangle sensor is concealed by a surface of the reservoir to preventexhaust heat from the radiator from thermally damaging the inclinationangle sensor.
 18. The arrangement structure according to claim 16,wherein the cross member is approximately an inverse U-shape as viewedfrom the side with a lower portion of the cross member being welded tothe front down frame members.
 19. The arrangement structure according toclaim 18, wherein the inclination angle sensor includes a float having asemicircular shape that is pivotally mounted on a swinging shaftmounting nut with a damper being provided for limiting the swingingmovement of the float.
 20. The arrangement structure according to claim19, wherein the swinging shaft of the float is arranged substantiallyparallel to a longitudinal direction of the vehicle body.